A joint infection can cause a severe and potentially destructive form of arthritis, often referred to as septic arthritis. Bacterial joint infections can be caused by a number of different organisms and can occur in both natural and artificial joints (i.e., after a knee replacement). The bacteria can enter the joint by traveling through the blood or by direct entrance into the joint from trauma or from surgery. Previous joint surgery and a depressed immune system increase the risk of the disorder.
In most cases, antibiotics are given following a surgical debridement and lavage. Drainage of the joint fluid may require repeated needle aspiration or, for some deep joints (i.e., hip, shoulder), surgical placement of a drainage tube.
As mentioned above, patients who have artificial joints are at a greater risk of developing a joint infection. Approximately 0.5 to 1 percent of patients with replacement joints will develop such an infection after surgery. Infections can occur early in the course of recovery from joint replacement surgery (within the first two months) or much later. Unfortunately, artificial joint infections may be difficult to treat. This is due, at least in part, to the development of a biofilm within the joint. A biofilm develops when bacteria adhere to the solid surface of the artificial joint. Biofilm makes it difficult for the bacteria to be identified and destroyed by the body's defenses or by antibiotic medications. Treatment of artificial joint infections can also involve surgery to remove infected tissue. In many cases, the artificial joint must be removed, at least temporarily. After a period of antibiotic treatment and once the infection is controlled, a new prosthesis may be placed. However, in some cases, it is not possible to replace the prosthetic joint, and surgery to fuse the bones or amputate the extremity is recommended instead.